Method and apparatus for optimizing running performance of an individual

ABSTRACT

A method and device for optimizing running performance for an individual. Movements of a foot are monitored using one or more accelerometers. The data is transmitted to a portable electronic processing device, e.g. in the form of a cellular phone, where the data is processed to derive a movement pattern of the foot. Based on a comparison of the derived movement pattern and an optimal movement pattern, the portable electronic processing device provides feedback to the individual in order to adjust the movement pattern of the foot of the individual, thereby improving a running performance. Thereby the risk of injuries and overload of muscles, joints and tendons can be reduced.

TECHNICAL FIELD

The present invention relates to a method for optimizing runningperformance of an individual, e.g. with respect to allowing theindividual to spend energy in an efficient manner, and/or with respectto avoiding injuries, such as nagging injuries, or undesired loads onjoints, muscles or tendon.

BACKGROUND

It is widespread to exercise by running, e.g. by cross country runningor jogging. In order to ensure that a runner gains the most of his orher training, it is important that the runner runs in a correct manner,e.g. in terms of how a stride is performed and the pose of the torso.The running form of a runner may, e.g., be tested by letting the runnerrun on a treadmill while wearing suitable sensors coupled to stationarydata gathering and processing equipment. Based on such a test, generaladvice regarding running form may be provided to the runner. However, itis not possible to check whether or not the runner sticks to the generaladvice, once the runner is doing actual training at a later point intime, e.g. in a training pass.

EP 2 025 368 A2 discloses a sports training system comprising at leastone monitor and a portable electronic processing device for receivingdata from the at least one monitor and providing feedback to anindividual based on the received data. Thereby the performance of theindividual can be improved. The sports training system of EP 2 025 368A2 does not provide feedback to the individual which allows theindividual to improve his or her running style in order to minimize therisk of injury or spending energy in an efficient manner.

SUMMARY

It is an object to provide a method for optimizing running performancewhich allows an individual to, adjust his or her running style in orderto improve running performance or in order to minimize the risk ofinjuries.

The foregoing and other objects are achieved by the features of theindependent claims. Further implementation forms are apparent from thedependent claims, the description and the figures.

According to a first aspect the above and further objects and advantagesare obtained by a method for optimizing running performance for anindividual, the method comprising:

-   -   monitoring movements of a foot of the individual while running,        using one or more accelerometers,    -   transmitting data obtained during the monitoring step from the        one or more accelerometers to a portable electronic processing        device,    -   the portable electronic processing device deriving a        three-dimensional movement pattern of the foot of the        individual, based on the data obtained during the monitoring        step,    -   the portable electronic processing device comparing the derived        movement pattern of the foot of the individual to an optimal        movement pattern, and    -   the portable electronic processing device providing real-time        voice feedback repeatedly during a training pass to the        individual, based on the comparing step, and in order to adjust        the movement pattern of the foot of the individual, the        real-time feedback being in the form of voice feedback        instructing the individual to adjust the individual's movement        pattern, thereby improving the individual's running performance.

In a first possible implementation of the first aspect the portableelectronic processing device provides real-time voice feedbackrepeatedly during a training pass to the individual, based on thecomparing step, and in order to confirm the movement pattern of the footof the individual, the real-time feedback being in the form of voicefeedback instructing the individual to confirm the individual's movementpattern, thereby maintaining the individual's running performance.

In a second possible implementation of the first aspect monitoringmovements, transmitting data, deriving a movement pattern, comparing thederived movement pattern to an optimal movement pattern, and providingfeedback are performed in real time.

In a first possible implementation of the first aspect providingfeedback comprises providing vibration feedback.

In a first possible implementation of the first aspect the providingfeedback includes instructions for the individual to change his/hermovement pattern in the form of simple instructions that may or may notdirectly reflect the deviation between the ideal movement pattern andthe individual's movement pattern.

In the present context the term ‘individual’ should be interpreted tomean a human being who is performing exercise by running.

In another possible implementation of the first aspect, movements of afoot of the individual are initially monitored, while the individual isrunning in a training pass. This is achieved by means of one or moreaccelerometers, preferably arranged at or near the foot of theindividual, such as attached to the a shoe, in the sole of a shoe, in asock or directly mounted on the foot of the individual. Theaccelerometers, thus, measure accelerations of the foot as a function oftime.

In another possible implementation of the first aspect the data obtainedby the accelerometers is transmitted to a portable electronic processingdevice. The portable electronic processing device is preferably carriedby the individual, thereby allowing the data to be transmitted while theindividual is running. The transmission may be performed wirelessly,e.g. using a WiFi signal, a Bluetooth signal, or any other suitable kindof wireless signal. As an alternative, the portable electronicprocessing device may be hardwired to the accelerometers, and thetransmission may take place via the hardwired connection. Thetransmission may be performed continuously, or data may be transmittedin batches at predefined time intervals.

In another possible implementation of the first aspect the portableelectronic processing device derives a three-dimensional movementpattern of the foot of the individual, based on the data obtained fromthe monitoring step, i.e. based on the data relating to the accelerationof the foot. Accordingly, this step results in a three-dimensionalpattern, which reflects how the foot moves, e.g. during a stride. Inparticular, the three-dimensional pattern reflects accelerations, andthereby forces, acting on the foot as the foot moves while theindividual runs, e.g. in the course of a stride.

In another possible implementation of the first aspect the electronicprocessing device compares the derived movement pattern of the foot ofthe individual to an optimal movement pattern. The optimal movementpattern may, e.g., be a pattern which is known to provide an optimalutilization of the energy spent by the individual and/or which minimizesthe risk of injuries, such as nagging injuries or undesired loads onmuscles, joints or tendons. The optimal pattern may be a universalpattern, or it may be an individual pattern, which is optimized withrespect to characteristics and/or previous performance of theindividual.

In another possible implementation of the first aspect the comparisonreveals to which extent the derived movement pattern of the foot of theindividual follows the optimal movement pattern, and thereby whether ornot the individual runs in an optimal manner. Furthermore, in the casethat the derived movement pattern differs from the optimal movementpattern, the comparison may further reveal in which manner the derivedmovement pattern differs from the optimal movement pattern, and therebywhat the individual should change in order to improve the movementpattern, i.e. to adjust the movement pattern in the direction of theoptimal movement pattern.

In another possible implementation of the first aspect the portableelectronic processing device provides feedback to the individual, basedon the comparing step. The feedback is of a kind which seeks to adjustthe movement pattern of the foot of the individual in such a manner thatthe running performance of the individual is improved, i.e. to reducethe difference between the derived movement pattern and the optimalmovement pattern. The the feedback is provided while the individual isrunning, the individual is allowed to adjust the running style duringthe training pass, since is much more efficient than providing feedbackwhen the individual has completed a training pass, and expecting theindividual to remember the feedback when performing the next trainingpass.

Since the feedback is based on the comparing step, it is based on howmuch and in which way the derived movement pattern of the foot differsfrom the optimal movement pattern. Thus, the provided feedbackpreferably informs the individual in which manner the individual shouldchange his or her running style in order to obtain a movement pattern ofthe foot which is identical to, or at least more similar to, the optimalmovement pattern.

When the three-dimensional movement pattern of the foot is derived, theportable electronic processing device may use further information, whichis not obtained by means of the one or more accelerometers. Forinstance, the portable electronic processing device may itself becapable of obtaining information, such as a position of the individual(in the case that the portable electronic processing device comprises aGPS module), time, distance, running velocity, altitude, etc.

Furthermore, personal information relating to the individual mayinitially be provided to the portable electronic processing device. Suchinformation may, e.g., include gender, age, maximum pulse, height,length of legs, weight, etc.

In another possible implementation of the first aspect the steps ofmonitoring movements, transmitting data, deriving a movement pattern,comparing the derived movement pattern to an optimal movement pattern,and providing feedback may be performed in real time. According to thisimplementation, the actual movement pattern of the foot of theindividual is continuously monitored and compared to the optimalmovement pattern, and feedback is repeatedly provided to the individualduring the training pass. Thus, the feedback is given during thetraining pass, and if the running style of the individual changes duringa training pass, e.g. because the individual gets tired, this can bedetected, and the individual is encouraged, via the feedback, to restorea running style which provides an optimal movement pattern of the foot.

The step of providing feedback may comprise providing audible feedback.According to this implementation, the feedback may advantageously beprovided via earphones coupled to the portable electronic processingdevice.

In an implementation the feedback is provided real-time in the form ofvoice feedback. The voice feedback may include instructions for theindividual how to adjust the individual's movement pattern.

Alternatively or additionally, the step of providing feedback maycomprise providing visual feedback, or any other suitable kind offeedback, which the individual is capable of perceiving.

In another possible implementation of the first aspect the portableelectronic processing device may be a cellular phone, such as asmartphone. As an alternative, the portable electronic processing devicemay be a watch, a heart rate monitor, an audio player, or any othersuitable kind of portable device, which is capable of performingelectronic processing of measurement data, and of providing a feedback.In the case that the portable electronic processing device is a cellularphone, a watch or another kind of device having a display, the feedbackmay include written statements, or illustrative diagrams or pictogramsprovided via the display.

It is a further object to provide a method for optimizing runningperformance which allows an individual to, while running, adjust his orher running style in order to optimize energy consumption.

According to a second aspect the above and further objects andadvantages are obtained by a method for optimizing running performancefor an individual comprising:

-   -   monitoring movements of the chest of the individual while        running, using one or more accelerometers arranged at the chest        of the individual,    -   transmitting data obtained during the monitoring from the one or        more accelerometers to a portable electronic processing device        carried by the individual,    -   transmitting data obtained during monitoring from the one or        more accelerometers to the portable electronic processing        device, and    -   the portable electronic processing device calculating an        instantaneous power spent to propel the individual's body, based        on the transmitted data,    -   the portable electronic processing device providing real-time        voice feedback repeatedly during a training pass to the        individual, based on the calculated instantaneous power and in        order to minimize the instantaneous power spent to propel the        individual's body.

In another possible implementation of the second aspect the real-timefeedback is in the form of voice feedback instructing the individual toadjust the individual's movement pattern or running style, therebyimproving the individual's running performance.

In another possible implementation of the second aspect the real-timefeedback encourages the individual to run in a more energy efficientmanner.

In another possible implementation of the second aspect the real-timefeedback encourages the individual to run in a manner which minimizesthe average power spent to propel the individual's body at a givenrunning velocity.

In another possible implementation of the second aspect the portableelectronic device monitoring movements of the chest of the individual,using one or more accelerometers arranged at the chest of theindividual,

-   -   transmitting data obtained during the monitoring step from the        one or more accelerometers to the portable electronic processing        device, and    -   the portable electronic processing device calculating an        instantaneous power spent to propel the individual's body, based        on the transmitted data,

wherein the step of the portable electronic processing device providingfeedback to the individual is further based on the calculatedinstantaneous power.

In another possible implementation of the second aspect the individualis provided with one or more further accelerometers. The furtheraccelerometers are arranged at the chest of the individual, and therebyaccelerations of the chest of the individual are monitored while theindividual is running.

Similarly to the data relating to the movements of the foot, the datarelating to the movements of the chest is transmitted to the portableelectronic processing device, and the portable electronic processingdevice processes the received data. Thereby the portable electronicprocessing device calculates an instantaneous power spent to propel theindividual's body, based on the transmitted data. The feedback providedto the individual is further based on the calculated instantaneouspower.

In another possible implementation of the second aspect a measure isobtained for the power which the individual is currently spending inpropelling the body of the individual. This measure indicates whether ornot the individual is spending energy in an efficient manner. Therefore,providing feedback based on the calculated instantaneous power mayadvantageously include providing feedback in order to improve theefficiency of the energy consumption of the individual.

A measurement of power spent to propel the body of an individual issometimes referred to as a ‘Watt measurement’.

In another possible implementation of the second aspect the method mayfurther comprise the steps of:

-   -   calculating an average power spent to propel the individual's        body over a predefined time interval, and    -   deriving a running efficiency indicator, based on the calculated        average power, and on a running velocity of the individual,        wherein the step of the portable electronic processing device        providing feedback to the individual is further based on the        derived running efficiency indicator. According to this        embodiment, the individual is encouraged to run in a more energy        efficient manner, i.e. in a manner which minimizes the average        power spent to propel the individual's body at a given running        velocity.

In another possible implementation of the second aspect the method maybe performed in the following manner. A reference power, or referencewattage, for the individual runner may be provided, in order to attemptto provide an absolute calibrated power estimation. One or more sensors,in the form or accelerometer(s), is/are mounted on the torso of therunner, close to the center of gravity of the torso. Theaccelerometer(s) provide(s) a three-dimensional acceleration vector,representing a three-dimensional acceleration pattern of the torso. Thethree-dimensional accelerometer output is conditioned in order to removeDC components of the signal. Such DC components are normally due togravity. Subsequently, the output is transformed to provide a resultingspace acceleration vector for the torso acceleration. The torsoacceleration is then multiplied by the body mass of the individual, inorder to obtain the force which moves the torso. A dynamics torsovelocity is obtained by integrating the torso acceleration with respectto time. This may, e.g., be done using a low pass filter, such as afirst order low pass filter. The product of the force and the torsovelocity results in the instantaneous power that is spent for propellingthe individual's body forwards. Averaging the power over predefined timeintervals provides a stable measure for power spent. Comparing thismeasure for the power spent to the running velocity provides a runningefficiency indicator.

In another possible implementation of the first or second aspect thestep of deriving a movement pattern of the foot may comprise derivingpoints of impact and/or duration of impact on the foot between the footand the ground during an impact phase of a stride.

In another possible implementation of the first or second aspect astride is sometimes divided into a number of phases, such as an impactphase where the foot contacts the ground, and a swing phase where thefoot is moved above the ground. During the impact phase it is importanthow the foot is moved, since the loads on muscles, joints and tendonstend to be significant during this phase. Therefore, moving the foot inan incorrect manner, or in a less than optimal manner, during the impactphase may very well result in overload or undesired loads, and therebythe risk of injuries is increased.

It can be an advantage to monitor points of impact between the foot andthe ground, and to monitor duration of impact between the foot and theground. For instance, a first accelerometer may detect the impactbetween the heel and the ground, as well as the duration of this impact.A second accelerometer may detect the impact between the mid foot andthe ground, as well as the duration of this impact. A thirdaccelerometer may detect the impact between the front foot and theground, as well as the duration of this impact. Based on thesemeasurements, a movement pattern of the foot, during the impact phase,can be derived. The movement pattern may include exactly where on thefoot the impacts between the heel, the mid foot and the front footoccur, and the respective durations of each of these impacts. Thus, aquality of the impact phase can be measured, based on the measuredaccelerations, and, e.g., based on an angle between the foot and theground at the initial impact between the heel and the ground (dorsalflexion and/or plantar flexion of the foot), and/or based on whether theimpact takes place along an outer side or an inner side of the foot,and/or based on rotational or torsional movements of the back part ofthe foot (pronation or supination), and/or based on sideways movementsof the heel (calcaneus inversion or eversion), and/or based onacceleration and/or angle between the foot and the ground duringtermination of the impact phase.

As an alternative, a single three-dimensional accelerometer, e.g.mounted on the foot, may provide the data described above.

In particular, the accelerometers may provide information regarding thespeed, position and impact time of the foot, during the impact phase aswell as during the swing phase.

The information listed above is valuable with respect to evaluating therisk of injuries or undesired loads on muscles, joints and tendons, dueto an inappropriate running style. It is also valuable with respect toevaluating whether or not the energy spent by the individual is spent inan efficient manner.

Thus, based on the comparison between the derived movement pattern andthe optimal movement pattern, the feedback to the individual could,e.g., be of the form: “Reduce the length of your stride”; “Leanforwards”; “Move impact further towards front foot”; “Move impactfurther towards mid foot”, etc.

The step of deriving a movement pattern of the foot may comprisederiving vertical and horizontal position of the foot during a swingphase of a stride. This allows, e.g., the lifting of the leg, includinghip flexion at forward movement, and the angle of the foot (dorsalflexion) during the terminal part of the swing phase to be evaluated.

Alternatively or additionally, the following information may be obtainedduring the swing phase: Acceleration and/or sideways movements of thefoot (and thereby the lower part of the leg) during the initial part ofthe swing phase. This provides information regarding ‘heel kick’,differences between movements of the left and right leg at maximumextension of the hip and flexion of the knee. Acceleration andsubsequent deceleration of the foot during the swing phase. Thisprovides information regarding force changes, and thereby stress loadson the hip bender and the muscles at the back of the knee, as well asregarding the maximum movement of the leg, and thereby the extension orlength of the leg.

Furthermore, the step of deriving a movement pattern may includeobtaining information regarding stride length, stride frequency,duration of impact phase and/or duration of swing phase. For instance, astride length may be derived on the basis of a stride count obtainedfrom the data provided by the accelerometer(s) and a position and/orvelocity obtained by means of a GPS module of the portable electronicprocessing device.

The step of deriving a movement pattern of the foot may comprisederiving a pose angle of a torso of the individual. The pose angle ofthe torso is important with respect to the stride length and the energyconsumption during a stride. Adjusting the pose angle of the torso maytherefore result in a more efficient energy consumption.

In another possible implementation of the first or second aspect themethod may further comprise the step of the portable electronicprocessing device transmitting processed data to a central database.According to this embodiment, data originating from a plurality oftraining passes, possibly performed by a plurality of individuals, isgathered in the central database. This allows the data to be morethoroughly processed after a training pass has been completed. Itfurther allows data originating from one training pass to be compared todata originating from other training passes performed by the individual,and possibly to training passes performed by other individuals. This maybe used for defining ‘optimal movement patterns’ and/or for adjustingexisting ‘optimal movement patterns’. Thereby the system can be improvedover time in the sense that the ‘optimal movement pattern’ which thederived movement pattern is compared to, is continuously improved toreflect a running style which is truly optimal, based on actualmeasurements performed on actual runners performing actual trainingpasses. The improved optimal movement patterns may, e.g., be obtained bymeans of artificial intelligence (AI), e.g. using pattern recognitionand classification of running styles.

In another possible implementation of the first or second aspect thedatabase may further comprise data obtained in a research laboratory.This will allow more data to be measured than will be practical during areal training pass, and thereby additional knowledge regarding therunning style of a given individual can be obtained.

In another possible implementation of the first order second aspect thestep of comparing may comprise comparing the derived movement pattern toa movement pattern derived previously during the same training pass,thereby obtaining a measure for a change in the movement pattern as afunction of time, and wherein the step of providing feedback comprisesgenerating a warning when changes in the movement pattern exceeds apredefined threshold.

According to this implementation, the running style of the individual ismonitored during the course of a training pass. It is normally easier tomaintain a correct running style at the beginning of a training pass,where one is not tired. As the training pass proceeds, the individualgrows tired and possibly less concentrated. Thereby it becomesincreasingly difficult to run in a correct manner, and the risk ofinjuries and/or less efficient energy consumption is increased. It istherefore an advantage to monitor the running style of the individual,in order to detect when changes in the running style occur, and toprovide feedback to the individual which encourages him or her tomaintain an optimal or a correct running style during the entiretraining pass.

For instance, the comparison may reveal that the stride frequency isincreasing or decreasing. In this case the feedback to the individualcould, e.g., be: “Your stride frequency is increasing/decreasing, pleasedecrease/increase the stride frequency”. Or the feedback could simply bean alarm indicating that the stride frequency is changing. As anotherexample, the comparison may reveal that the point of impact between thefoot and the ground is moving backwards towards the heel. In this casethe feedback to the individual could, e.g., be: “Your impact is movingbackwards, please ensure landing further towards the mid foot”.

The method according to the first or second aspect may further compriseobtaining further data regarding the individual. Such data may, e.g.,include running velocity of the individual and/or the heart rate of theindividual. Such data may be used, along with the data obtained from theaccelerometers, for calculating stride length and/or energy consumptionper unit length the body of the individual is propelled forwards.

According to an implementation of the first or second aspect, the methodmay be performed in the following manner. Data relating tothree-dimensional accelerations of the foot of an individual is obtainedby means of one or more accelerometers, e.g. a three-dimensionalaccelerometer, mounted at or near the foot of the individual. The datais transmitted to a portable electronic processing device, where it isconditioned for the removal of a DC component, which originates from theforce of gravity acting on the foot. Then the conditioned data istransformed in order to provide a resulting space acceleration vectorfor the foot. The acceleration is multiplied by a dynamic mass of thefoot and leg, thereby obtaining a foot impact force, representing theimpact of the forces acting on the foot, except for the gravitationalforce. A foot impact history can be derived from the processed data, andbased on the foot impact history information regarding maximum impactforce on the foot, duration of impact between the foot and the ground,foot imprint characteristics, etc. can be derived. The result may bereferred to as a ‘Key Performance Index’.

According to a third aspect the above and further objects and advantagesare obtained by a portable electronic device for optimizing runningperformance for an individual, the portable electronic device comprisinga processor and a user interface the processor being configured toconfigured to:

-   -   receive data obtained from the one or more accelerometers        associated with a foot of the individual,    -   monitor movements of a foot of the individual while running        during a training pass, from a signal from the one or more        accelerometers,    -   derive a three-dimensional movement pattern of the foot of the        individual, based on the data obtained during monitoring,    -   compare the derived movement pattern of the foot of the        individual to an optimal movement pattern, and    -   to providing real-time voice feedback repeatedly during the        training pass to the individual, based on the comparison, and in        order to adjust the movement pattern of the foot of the        individual, the real-time feedback being in the form of voice        feedback instructing the individual to adjust the individual's        movement pattern.

According to a fourth aspect the above and further objects andadvantages are obtained by portable electronic device for optimizingrunning performance for an individual during a training pass, theportable electronic device comprising a processor and a user interfacethe processor being configured to configured to:

-   -   receive data obtained from one or more accelerometers arranged        at the chest of the individual,    -   monitor movements of the chest of the individual while running,        using the data obtained from the one or more accelerometers,    -   calculate an instantaneous power spent to propel the        individual's body, based on the received data,    -   provide real-time voice feedback repeatedly during a training        pass to the individual, based on the calculated instantaneous        power and in order to minimize the instantaneous power spent to        propel the individual's body.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in further detail with reference tothe accompanying drawings, in which

FIG. 1 is a block diagram illustrating a method according to a firstembodiment of the invention,

FIG. 2 is a block diagram illustrating a method according to a secondembodiment of the invention,

FIG. 3 is a front view of an individual carrying sensors for use in amethod according to an embodiment of the invention,

FIG. 4 is a side view of the individual of FIG. 3,

FIGS. 5 and 6 show a sensor arranged on a shoe,

FIGS. 7-10 show examples of feedback provided to an individual, and

FIG. 11 shows measurements performed by a three-dimensionalaccelerometer as a function of time.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a method according to a firstembodiment of the invention. A data stream signal 1 is obtained from athree-dimensional accelerometer arranged on or near the foot of anindividual. The data stream signal 1 is supplied to a conditioning unit2, where a dynamic space vector is calculated, and the DC component ofthe signal is removed, the DC signal originating from gravity acting onthe foot. Thereby the resulting space acceleration vector acting on thefoot is obtained. The space acceleration vector is supplied to amultiplier 3, where it is multiplied by a dynamic mass of the foot andleg, thereby obtaining an impact force acting on the foot.

The foot impact force is analyzed in order to obtain Key Performanceindices 4, e.g. representing maximum impact force, ground contactduration, foot imprint characteristics, etc., for each stride. Based onthis, a movement pattern of the foot can be derived. The derivedmovement pattern can be compared to an optimal movement pattern, andbased on the comparison a feedback can be generated for the individual,in order to encourage the individual to run in an optimal manner. Thefeedback is provided real-time in the form of voice feedback. The voicefeedback may include oral instructions for the individual how to adjustthe individual's movement pattern. The voice feedback may be providedrepeatedly during a training pass so that the individual is coached in away similar to having a personal trainer. The feedback may also includevibration feedback.

FIG. 2 is a block diagram illustrating a method according to a secondembodiment of the invention. A data stream signal 5 is obtained from athree-dimensional accelerometer arranged at or near a torso of anindividual. Preferably, the three-dimensional accelerometer is arrangedat or near the center of gravity of the torso. The data stream signal 5is supplied to a conditioning unit 6, where a resulting spaceacceleration vector is calculated, representing a torso acceleration.Calculating the resulting space acceleration vector includes removing aDC signal originating from gravity acting on the individual. Theresulting space acceleration vector is supplied to a multiplier 7, whereit is multiplied by a mass of the body of the individual, therebyobtaining a force which causes the movement of the torso.

Simultaneously, the resulting space acceleration vector is supplied toan integrator 8, e.g. in the form of a first order low pass filter,where the resulting space acceleration vector is integrated, therebyobtaining a dynamic torso velocity.

The calculated force and the obtained dynamic torso velocity aresupplied to a multiplier 9, where they are multiplied, thereby obtainingan instantaneous power, which the individual is spending in order topropel the body of the individual over the ground. Averaging thecalculated instantaneous power over a predefined time interval, e.g.10-20 seconds, provides a stable measure for power spent by theindividual. This average power, compared to running velocity, provides arunning efficiency indictor.

The running efficiency indicator may, e.g., be compared to a referencerunning efficiency. The reference running efficiency may be a universalreference, or it may be a reference which is specific for theindividual. Based on the comparison, or simply based on the runningefficiency indicator, a feedback can be generated for the individual, inorder to encourage the individual to run in a more efficient manner.

FIG. 3 is a front view of an individual 10 carrying sensors for use in amethod according to an embodiment of the invention. The individual 10carries a first sensor 11, mounted on a shoe worn by the individual 10,and a second sensor 12 arranged near a center of gravity of the torso ofthe individual 10. The individual 10 further carries a portableelectronic processing device in the form of a cellular phone 13 mountedon the arm of the individual 10.

The first sensor 11 and the second sensor 12 are both in the form ofthree-dimensional accelerometers. Thus, when the individual is running,the first sensor 11 measures three-dimensional accelerations of the footof the individual 10. The first sensor 11 supplies the measured data tothe cellular phone 13, and the cellular phone 13 processes the data,thereby deriving a movement pattern of the foot, e.g. identifying impactforce and/or impact time between the foot and the ground during astride. The derived movement pattern is compared to an optimal movementpattern. Based on the comparison, a feedback is provided to theindividual 10, in order to encourage the individual to run in such amanner that the foot is moved in an optimal manner.

Simultaneously, the second sensor 12 measures three-dimensionalaccelerations of the torso of the individual 10. The second sensor 12supplies the measured data to the cellular phone 13, and the cellularphone 13 processes the data in order to derive a measure for theinstantaneous energy spent by the individual 10 for propelling theindividual 10 forwards. Based on the derived instantaneous energy, afeedback is provided to the individual 10, in order to encourage theindividual 10 to run in a more energy efficient manner.

FIG. 4 is a side view of the individual of FIG. 3.

FIGS. 5 and 6 show detailed views of the first sensor 11 shown in FIGS.3 and 4. It can be seen that the first sensor 11 is attached at a topsurface of the shoe, via the shoelaces. Thereby the first sensor 11closely follows the movements of the foot, when the individual isrunning, and the first sensor 11 is, accordingly, capable of accuratelymeasuring three-dimensional accelerations of the foot.

FIG. 7 is a front view of a cellular phone 13 for use in performing amethod according to an embodiment of the invention. The cellular phone13 has an app installed thereon, which allows the cellular phone 13 toprocess data received from sensors, such as the first 11 and second 12sensors illustrated in FIGS. 3-6, and to provide feedback to anindividual, based on the processed data, in the manner described above.

In FIG. 7 feedback for the individual is displayed at a screen of thecellular phone 13, in the form of four score bars 14, each representinga parameter which influences the running style of the individual, andwritten feedback instructions 15.

Score bar 14 a represents deceleration of the individual as aconsequence of impact between the foot of the individual and the groundwhen the individual is running. The score bar 14 a shows that thedeceleration is approximately 15%, i.e. that the running velocity of theindividual is decreased by 15% when an impact occurs between the foot ofthe individual and the ground. The higher the deceleration, the moreenergy is required in order to restore the previous running velocity.Accordingly, the deceleration is a measure for a part of the energyrequired in order to propel the body of the individual forwards. If therunning style can be changed in a manner which reduces the deceleration,the energy consumption in order to run a specific distance at a specificvelocity can be reduced.

A deceleration of 15% is relatively low, and accordingly, the individualmay be instructed to run in a manner which slightly reduces thedeceleration, or the feedback to the individual may be that thedeceleration is fine, and that no adjustments in this regard arerequired.

Score bar 14 b represents an overall running technique score of theindividual. The running technique score may be calculated on the basisof various measured parameters, resulting in a derived movement patternof the foot of the individual. The measured parameters may, e.g.,include magnitude and/or position of an impact between the foot and theground, duration of the impact, acceleration of the foot during theswing phase, etc. The derived movement pattern is compared to an optimalmovement pattern, and the running technique score is derived on thebasis of this comparison. The score bar 14 b reveals that the runningtechnique score is approximately 68%, i.e. that the running techniquescore is approximately 68% of the optimal running technique score. Thisindicates that the running technique is good, but improvements may bedesired.

The optimal running technique score may be a personal goal, i.e. eachindividual may have his or her personal optimal running technique score,which is calculated or selected on the basis of specific and personalfeatures or limits for the individuals. As an alternative, the optimalrunning technique score may be a universal score, which represents aperfect running style.

Score bar 14 c represents stride frequency, in the form of a number ofstrides per minute performed by the individual while running. It ispreferred that the stride frequency is higher than 180 strides perminute. Therefore 154 strides per minute is relatively low, and theindividual should be instructed to increase the stride frequency.

Score bar 14 d represents a G force applied to the foot of theindividual during an impact between the foot and the ground. A high Gforce indicates that the foot is affected to a great extent during theimpact, and that there is therefore a high risk of injuries or overloadon muscles, joints or tendons. Score bar 14 d indicates a low score,thereby indicating such a high G force.

Each of the score bars 14 includes a bar, which may advantageously becolour coded, and a smiley. This allows the individual to, at a glance,determine whether one or more of the parameters is far off and needsattention.

The written feedback 15 is in the form of a specific and concrete adviceto the individual regarding how to change the running style in order torun in a more optimal manner, e.g. with respect to avoiding injuries oroverload of muscles, joints and tendons, and/or with respect to spendingenergy in an optimal manner. In FIG. 7 the written feedback 15 is“shorter stride” and “lean forward”. Thus, the app instructs theindividual to take shorter strides, and to lean forwards. This willresult in the individual taking off at a point of the foot which iscloser to the front part of the foot. This will decrease thedeceleration and increase the stride frequency. Thus, the writtenfeedback 15 addresses the problems identified and described above withreference to the score bars 14 a, 14 b, 14 c.

FIG. 8 is also a front view of a cellular phone 13, having an appinstalled thereon, which allows the cellular phone 13 to be used inperforming a method according to an embodiment of the invention,essentially as described above with reference to FIG. 7.

In FIG. 8 feedback for the individual is displayed on a screen of thecellular phone 13, in the form of marks illustrated on the feet of theindividual, representing the parts of the feet which are most affectedduring landing 16 and take-off 17, respectively. It can be seen fromFIG. 8 that the individual tends to land on an outer part of the foot,and take off at an inner and front part of the foot. This generallyrepresents a desired running style. A specific and concrete feedback tothe individual, based on this information, could, e.g., be “you aredoing good—keep it up”.

FIG. 9 is also a front view of a cellular phone 13, having an appinstalled thereon, which allows the cellular phone 13 to be used inperforming a method according to an embodiment of the invention,essentially as described above with reference to FIG. 7.

In FIG. 9 feedback for the individual is displayed on a screen of thecellular phone 13, in the form of a list of parameter values, eachproviding information regarding a parameter which is relevant withrespect to the running style and/or the performance of the individual,when the individual is running.

‘Time’ represents the time spent on the current training pass.

Running Watt′ represents the instantaneous power spent by the individualwhile propelling the body of the individual across the ground.

‘Heart rate’ represents the current heart rate of the individual.

‘Distance’ represents the distance covered by the current training pass.

‘Pace’ represents the instantaneous running velocity of the individual.

‘Average pace’ represents the average velocity of the individual, duringthe current training pass.

‘Strides’ represents the stride frequency.

‘Stride length’ represents the average length of the strides during ashort time period, such as 10-20 seconds.

‘Total strides’ represents the total number of strides during thecurrent training pass.

‘Altitude’ represents the altitude, where the individual is positioned.

‘Ascent’ represents the total climb performed by the individual duringthe current training pass.

‘Calories’ represents the amount of energy spent during the currenttraining pass.

Some of the information listed above may be derived from the dataprovided by the accelerometer(s), and some of the information may beprovided by the cellular phone 13. For instance, the cellular phone 13may provide information regarding time, distance covered, pace, averagepace, altitude and ascent.

Selecting one of the parameters by touching the corresponding area ofthe touch screen will result in more detailed information regarding theparameter to be displayed on the screen of the cellular phone 13.

FIG. 10 is also a front view of a cellular phone 13, having an appinstalled thereon, which allows the cellular phone 13 to be used inperforming a method according to an embodiment of the invention,essentially as described above with reference to FIG. 7.

In FIG. 10 feedback for the individual is displayed on a screen of thecellular phone 13, in the form of two graphs illustrating power 18 spentby the individual and pulse 19 of the individual, as a function of time.The image shown in FIG. 10 represents a complete training pass with aduration of approximately 40 minutes. The illustrated training passincludes interval training. It can be seen that the power issignificantly increased after approximately 10 minutes, and theincreased power level is maintained for approximately 5 minutes. Thenthe power is reduced to a basis level, which is maintained forapproximately 8 minutes. Then the power is once again increased to aneven higher level, and this higher level is maintained for approximately4 minutes, where the power level is decreased again. It can be seen thatthe power is allowed to temporarily drop to a level below the basislevel. Finally, after approximately 31 minutes, the power is increasedto an even higher level, and this very high level is maintained almostto the end of the training pass.

It can be seen that the pulse follows the power, in the sense that anincrease in the power results in a gradual increase in the pulse, and adecrease in the power results in a gradual decrease in the pulse.

FIG. 11 is a graph illustrating an output signal from athree-dimensional accelerometer arranged on the foot of an individual,who is running, as a function of time. Graph 20 shows accelerations ofthe foot along an x-direction, graph 21 shows accelerations of the footalong a y-direction, and graph 22 shows accelerations of the foot alonga z-direction.

Each of the large variations in the graphs 20, 21, 22 represents animpact between the foot carrying the three-dimensional accelerometer andthe ground. Thus, the graph of FIG. 11 represents three impacts betweenthe foot and the ground.

The data corresponding to the graph of FIG. 11 is supplied to a portableelectronic processing device, e.g. in the form of a cellular phone,where the data is processed, as described above, in order to obtain amovement pattern of the foot, and generate a feedback to the individual.

1. A method for optimizing running performance for an individual, themethod comprising: monitoring movements of a foot of the individualwhile running during a training pass, using one or more accelerometers,transmitting data obtained during the monitoring step from the one ormore accelerometers to a portable electronic processing device worn bythe individual, the portable electronic processing device deriving athree-dimensional movement pattern of the foot of the individual, basedon the data obtained during the monitoring of the movements of the foot,the portable electronic processing device comparing the derived movementpattern of the foot of the individual to an optimal movement pattern,and the portable electronic processing device providing real-time voicefeedback repeatedly during said training pass to the individual, basedon the comparing of the derived movement pattern of the foot of theindividual to the optimal movement pattern, and in order to adjust themovement pattern of the foot of the individual, said real-time voicefeedback being in the form of voice feedback instructing the individualto adjust the individual's movement pattern, thereby improving theindividual's running performance.
 2. A method according to claim 1,wherein the portable electronic processing device provides real-timevoice feedback repeatedly during a training pass to the individual,based on the comparing of the derived movement pattern of the foot ofthe individual to the optimal movement pattern, and in order to confirmthe movement pattern of the foot of the individual, said real-timefeedback being in the form of voice feedback instructing the individualto confirm the individual's movement pattern, thereby maintaining theindividual's running performance.
 3. A method according to claim 1,wherein the monitoring movements of the foot, transmitting data,deriving the movement pattern, comparing the derived movement pattern toan optimal movement pattern, and providing feedback are performed inreal time.
 4. A method according to claim 1, wherein thethree-dimensional movement pattern of the foot of the individual isderived in the form of a three-dimensional pattern which reflects howthe foot moves.
 5. A method according to claim 4, wherein the comparingof the derived movement pattern of the foot of the individual to theoptimal movement pattern reveals in which manner the derived movementpattern differs from the optimal movement pattern, and what theindividual should change in order to adjust the movement pattern in thedirection of the optimal movement pattern.
 6. A method according toclaim 5, wherein said real-time voice feedback informs the individualwhat the individual should change in order to adjust the movementpattern in the direction of the optimal movement pattern.
 7. A methodaccording to claim 1, wherein providing real-time voice feedbackincludes instructions for the individual to change his/her movementpattern in the form of simple instructions that may or may not directlyreflect the deviation between the ideal movement pattern and theindividual's movement pattern.
 8. A method according to claim 1, whereinthe portable electronic processing device is a cellular phone.
 9. Amethod according to claim 1, wherein the portable electronic processingdevice is a wrist worn device.
 10. A method according to claim 1,further comprising: monitoring movements of the chest of the individual,using one or more accelerometers arranged at the chest of theindividual, transmitting data obtained during the monitoring ofmovements of the chest of the individual from the one or moreaccelerometers to the portable electronic processing device, and theportable electronic processing device calculating an instantaneous powerspent to propel the individual's body, based on the transmitted data,wherein portable electronic processing device providing real-time voicefeedback to the individual is further based on the calculatedinstantaneous power.
 11. A method according to claim 10, furthercomprising: calculating an average power spent to propel theindividual's body over a predefined time interval, and deriving arunning efficiency indicator, based on the calculated average power, andon a running velocity of the individual, wherein the portable electronicprocessing device providing real-time voice feedback to the individualis further based on the derived running efficiency indicator.
 12. Amethod according to claim 1, wherein deriving the movement pattern ofthe foot comprises deriving points of impact and/or duration of impacton the foot between the foot and the ground during an impact phase of astride.
 13. A method according to claim 1, wherein deriving the movementpattern of the foot comprises deriving vertical and horizontal positionof the foot during a swing phase of a stride.
 14. A method according toclaim 1, wherein deriving the movement pattern of the foot comprisesderiving a pose angle of a torso of the individual.
 15. A methodaccording to claim 1, further comprising the portable electronicprocessing device transmitting processed data to a central database. 16.A method according to claim 1, wherein comparing the derived movementpattern of the foot of the individual to an optimal movement patterncomprises comparing the derived movement pattern to a movement patternderived previously during the same training pass, thereby obtaining ameasure for a change in the movement pattern as a function of time, andwherein providing real-time voice feedback comprises generating awarning when changes in the movement pattern exceeds a predefinedthreshold.
 17. A portable electronic device for optimizing runningperformance for an individual, the portable electronic device comprisinga processor and a user interface said processor being configured to:receive data obtained from the one or more accelerometers associatedwith a foot of the individual monitor movements of a foot of theindividual while running during a training pass, from a signal from saidone or more accelerometers, derive a three-dimensional movement patternof the foot of the individual, based on the data obtained duringmonitoring, compare the derived movement pattern of the foot of theindividual to an optimal movement pattern, and provide real-time voicefeedback repeatedly during said training pass to the individual, basedon the comparison, and in order to adjust the movement pattern of thefoot of the individual, said real-time feedback being in the form ofvoice feedback instructing the individual to adjust the individual'smovement pattern.
 18. A method for optimizing running performance for anindividual comprising: monitoring movements of the chest of theindividual while running, using one or more accelerometers arranged atthe chest of the individual, transmitting data obtained during themonitoring from the one or more accelerometers to a portable electronicprocessing device carried by the individual, transmitting data obtainedduring monitoring from the one or more accelerometers to the portableelectronic processing device, and the portable electronic processingdevice calculating an instantaneous power spent to propel theindividual's body, based on the transmitted data, the portableelectronic processing device providing real-time voice feedbackrepeatedly during a training pass to the individual, based on thecalculated instantaneous power and in order to minimize theinstantaneous power spent to propel the individual's body.
 19. A methodaccording to claim 18, wherein said real-time feedback is in the form ofvoice feedback instructing the individual to adjust the individual'smovement pattern or running style, thereby improving the individual'srunning performance.
 20. A method according to claim 18, wherein saidreal-time feedback encourages the individual to run in a more energyefficient manner.
 21. A method according to claim 18, wherein saidreal-time feedback encourages the individual to run in a manner whichminimizes the average power spent to propel the individual's body at agiven running velocity.
 22. A portable electronic device for optimizingrunning performance for an individual during a training pass, theportable electronic device comprising a processor and a user interfacesaid processor being configured to configured to: receive data obtainedfrom one or more accelerometers arranged at the chest of the individual,monitor movements of the chest of the individual while running, usingthe data obtained from said one or more accelerometers, calculate aninstantaneous power spent to propel the individual's body, based on thereceived data, provide real-time voice feedback repeatedly during atraining pass to the individual, based on the calculated instantaneouspower and in order to minimize the instantaneous power spent to propelthe individual's body.